Pump thrombosis is one of the major adverse events associated with the use of a left ventricular assist system (LVAS) in patients with advanced heart failure. We investigated the clinical implication of pump replacement because of thrombus formation. This study included 87 patients who underwent implantation of a Nipro (Toyobo) pulsatile extracorporeal LVAS intended as a bridge to transplantation and were alive more than 3 months after implantation. The pump of this device is translucent, and daily evaluation for signs of thrombus formation was performed. Pump replacement was performed for significant thrombus formation that became visible. Data collection including demographics as well as hematologic values were performed 1 day before (baseline) and 3 months after implantation, and all patients were followed for 2 years or until death. At 3 months after LVAS implantation, 41 patients (47.1%) had undergone pump replacement because of pump thrombus. Baseline body surface area <1.63m2 was a significant predictor of pump replacement (hazard ratio [HR] 2.15, P=0.04). At 3 months after implantation, there was a significantly higher incidence of stroke (P<0.05) as well as a significantly greater decrease in body weight (F=4.92, P=0.03) in patients who underwent pump replacement as compared to those without. The 2-year mortality after implantation was 26.4%. Multivariate Cox regression analysis showed that pump replacement within 3 months after implantation was an independent predictor of mortality (HR 2.50, P=0.03). In conclusion, pump replacement for thrombus formation may have a strong association with worse outcome. Our results reconfirm the clinical importance of device thrombus in the management of LVAS.
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